According to National Cancer Institute statistics, 41% of men and women alive today will be diagnosed with cancer at some point in their lives. The widespread occurrence of this disease underscores the need for improved anticancer regimens for the treatment of malignancy.
One important drug target is a group of proteins called kinases. Protein kinases are a large and diverse family of enzymes that catalyze protein phosphorylation and play a critical role in cellular signaling. They may exert positive or negative regulatory effects, depending upon their target protein. Protein kinases are involved in specific signaling pathways which regulate cell functions such as, but not limited to, metabolism, cell cycle progression, cell adhesion, vascular function, apoptosis, and angiogenesis. Malfunctions of cellular signaling have been associated with many diseases, the most characterized of which include cancer and diabetes. The regulation of signal transduction by cytokines and the association of signal molecules with proto-oncogenes and tumor suppressor genes have been well documented. Similarly, the connection between diabetes and related conditions, and deregulated levels of protein kinases, has been demonstrated. See e.g., Sridhar et al. Pharmaceutical Research, 17(11):1345-1353 (2000). Viral infections and the conditions related thereto also have been associated with the regulation of protein kinases. Park et al. Cell 101 (7), 777-787 (2000).
Phosphatidylinositol 3-kinase (PI3K or PIK3CA) is composed of an 85 kDa regulatory subunit and a 110 kDa catalytic subunit. The protein encoded by this gene represents the catalytic subunit, which uses ATP to phosphorylate PtdIns, PtdIns4P and PtdIns(4,5)P2. PTEN, a tumor suppressor which inhibits cell growth through multiple mechanisms, can dephosphorylate PIP3, the major product of PIK3CA. PIP3, in turn, is required for translocation of protein kinase B (AKT1, PKB) to the cell membrane, where it is phosphorylated and activated by upstream kinases. The effect of PTEN on cell death is mediated through the PIK3CA/AKT1 pathway.
PI3Kα has been implicated in the control of cytoskeletal reorganization, apoptosis, vesicular trafficking, proliferation and differentiation processes. Increased copy number and expression of PIK3CA is associated with a number of malignancies such as ovarian cancer (Campbell et al., Cancer Res 2004, 64, 7678-7681; Levine et al., Clin Cancer Res 2005, 11, 2875-2878; Wang et al., Hum Mutat 2005, 25, 322; Lee et al., Gynecol Oncol 2005, 97, 26-34), cervical cancer, breast cancer (Bachman, et al. Cancer Biol Ther 2004, 3, 772-775; Li et al., Breast Cancer Res Treat 2006, 96, 91-95; Saal et al., Cancer Res 2005, 65, 2554-2559; Samuels and Velculescu, Cell Cycle 2004, 3, 1221-1224), colorectal cancer (Samuels, et al. Science 2004, 304, 554; Velho et al. Eur J Cancer 2005, 41, 1649-1654), endometrial cancer (Oda et al. Cancer Res. 2005, 65, 10669-10673), gastric carcinomas (Byun et al., Int J Cancer 2003, 104, 318-327; Lee et al., Oncogene 2005, 24, 1477-1480), hepatocellular carcinoma (Lee et al., Oncogene 2005, 24, 1477-1480), small and non-small cell lung cancer (Tang et al., Lung Cancer 2006, 51, 181-191; Massion et al., Am J Respir Crit Care Med 2004, 170, 1088-1094), thyroid carcinoma (Wu et al., J Clin Endocrinol Metab 2005, 90, 4688-4693), acute myelogenous leukemia (AML) (Sujobert et al., Blood 1997, 106, 1063-1066), chronic myelogenous leukemia (CML) (Hickey and Cotter J Biol Chem 2006, 281, 2441-2450), and glioblastomas (Hartmann et al. Acta Neuropathol (Berl) 2005, 109, 639-642).
A number of PI3K inhibitors are presently undergoing clinical evaluation in patients with cancer, the details of which can be reviewed at the web site ClinicalTrials.gov. For example, human clinical trials are underway to evaluate a form of N-(3-{[(2Z)-3-[(2-chloro-5-methoxyphenyl)amino]quinoxalin-2(1H)-ylidene]sulfamoyl}phenyl)-2-methylalaninamide in patients with lymphoma (See trial NCT00486135), non-small-cell lung cancer (See trial NCT00692640), endometrial cancer (See trials NCT01013324 and NCT00756847) breast cancer (See trials NCT01042925 and NCT01082068) or other solid tumor (See trials NCT01357330, NCT01390818 and NCT01436565). In light the compound's established biological activity, optimized forms are needed to achieve maximal patient efficacy.